there are 9 seats for 1st person, 8 seats for 2nd(because 1st person is alreasy in one), 7 seats for 3rd etc.

so permutation (9,5) is 9x8x7x6x5.

Combination would be like asking how many pairs of people can you make from those 5. which would be (5x4)/(2x1)

so permutation (9,5) is 9x8x7x6x5.

Combination would be like asking how many pairs of people can you make from those 5. which would be (5x4)/(2x1)